From 02fa7fbe2e8e7aea3717adadc62303caf7a2662d Mon Sep 17 00:00:00 2001
From: Cuong Manh Le <cuong@windscribe.com>
Date: Sat, 29 Apr 2023 00:16:14 +0700
Subject: [PATCH] Workaround issue with weird DNS server when bootstraping

We see in practice on fresh new VM test, there's a DNS server that
return the answer with record not for the query domain.

To workaround this, filter out the answers not for the query domain.
---
 resolver.go | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/resolver.go b/resolver.go
index 084281c..f2a8424 100644
--- a/resolver.go
+++ b/resolver.go
@@ -140,11 +140,18 @@ func lookupIP(domain string, timeout int, withBootstrapDNS bool) (ips []string)
 	if timeout > 0 && timeout < timeoutMs {
 		timeoutMs = timeoutMs
 	}
+	questionDomain := dns.Fqdn(domain)
 	ipFromRecord := func(record dns.RR) string {
 		switch ar := record.(type) {
 		case *dns.A:
+			if ar.Hdr.Name != questionDomain {
+				return ""
+			}
 			return ar.A.String()
 		case *dns.AAAA:
+			if ar.Hdr.Name != questionDomain {
+				return ""
+			}
 			return ar.AAAA.String()
 		}
 		return ""
@@ -154,7 +161,7 @@ func lookupIP(domain string, timeout int, withBootstrapDNS bool) (ips []string)
 		ctx, cancel := context.WithTimeout(context.Background(), time.Duration(timeoutMs)*time.Millisecond)
 		defer cancel()
 		m := new(dns.Msg)
-		m.SetQuestion(domain+".", dnsType)
+		m.SetQuestion(questionDomain, dnsType)
 		m.RecursionDesired = true
 
 		r, err := resolver.Resolve(ctx, m)